Commitments and Contingencies - Revolving Credit Facility (Details)	1 Months Ended		12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2020 USD ($) credit_agreement	Dec. 31, 2019 USD ($)
Line of Credit Facility [Line Items]
Number of credit agreements | credit_agreement			2
Indemnification claims			$ 0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, current borrowing capacity		$ 500,000,000.0
Line of credit facility, maximum borrowing capacity	$ 2,000,000,000.0
Line of credit facility, additional borrowing capacity	500,000,000.0	500,000,000.0
Letter of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity				$ 50,000,000.0
Line of Credit
Line of Credit Facility [Line Items]
Debt covenant, minimum consolidated EBITDA	$ 2.50	$ 2.50
Minimum | Line of Credit
Line of Credit Facility [Line Items]
Debt covenant, consolidated leverage ratio	3.50	3.50
Minimum | Base Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate (percent)		0.125%
Basis spread on variable rate (percent)	0.50%
Minimum | Eurodollar | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate (percent)		1.125%
Basis spread on variable rate (percent)	1.50%
Maximum | Line of Credit
Line of Credit Facility [Line Items]
Debt covenant, consolidated leverage ratio	4.00	4.00
Maximum | Base Rate | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate (percent)		0.50%
Basis spread on variable rate (percent)	0.875%
Maximum | Eurodollar | Revolving Credit Facility
Line of Credit Facility [Line Items]
Interest rate (percent)		1.50%
Basis spread on variable rate (percent)	1.875%